The key to storing Type II urea resin sand molds is maintaining a stable temperature and humidity environment. This begins with ensuring the airtightness and basic temperature control of the storage space. Choose a well-sealed warehouse to prevent direct intrusion of moisture or drastic temperature fluctuations. Install sealant strips on doors and windows, lay moisture-proof mats on the floor, and insulate the walls and roof to minimize temperature and humidity fluctuations caused by heat exchange. Additionally, configure temperature and humidity control equipment based on the storage area's climatic characteristics. If humidity is high, install a dehumidifier to continuously remove moisture from the air. If temperatures are too low, which could affect the stability of Type II urea resin sand, install low-temperature heating equipment to maintain a suitable temperature range. Actively controlling the temperature and humidity within the warehouse provides a stable and fundamental protection for the sand molds.
Pretreatment of sand molds after curing is crucial for minimizing subsequent moisture absorption and strength degradation. After Type II urea resin sand molds are completed and reach the specified curing strength, they must be thoroughly cooled in a well-ventilated area. The molds should be moved to a warehouse only after their temperature has dropped to roughly the same level as the storage environment. If the molds carry residual heat into storage, condensation will form on their surfaces due to the temperature difference, which can easily lead to moisture absorption and a decrease in strength. After the molds have cooled, they can be lightly coated with a special moisture-proofing agent, depending on the storage duration. This agent forms a thin, breathable protective film on the surface, preserving the micro-outgassing within the mold while preventing moisture from entering. This is particularly suitable for storage in high-humidity environments, providing an additional moisture barrier.
The stacking method and support structure design during storage can prevent deterioration of the molds due to moisture exposure or pressure. Wooden or plastic pallets should be used for support during storage to prevent direct contact between the molds and the ground. Even with a moisture-proof mat, prolonged contact can still cause moisture to seep through the ground, leading to moisture absorption at the bottom of the molds. Pallets create an elevated space, reducing the risk of moisture absorption. When stacking sand molds, the height must be controlled to prevent the weight of the upper layer from causing deformation of the lower layer. A certain amount of space should be left between adjacent sand molds to allow for gentle air circulation and prevent moisture from accumulating in the gaps. Sand molds with complex structures or thin walls should be secured with separate supports to prevent cracking due to uneven stress during stacking, further ensuring the structural integrity of the sand molds during storage.
Dynamic monitoring and timely adjustment of ambient temperature and humidity are crucial for preventing temperature and humidity fluctuations from affecting sand mold performance. Temperature and humidity sensors are deployed in various areas of the storage warehouse (such as corners, at the top and bottom of the sand mold stacks), collecting real-time environmental data and transmitting it to a control terminal. Staff can use the terminal to monitor temperature and humidity trends at any time. If humidity is rising, the dehumidifier should be increased in time or the warehouse should be checked for leaks in seals. If the temperature is too low, heating equipment can be activated to slowly increase the temperature to prevent sudden temperature fluctuations that may cause stress within the sand molds. At the same time, temperature and humidity data should be regularly recorded. Historical data should be used to analyze patterns of change and predict potential temperature and humidity anomalies. For example, dehumidification should be strengthened before the rainy season arrives, and insulation measures should be checked before winter temperatures drop, achieving proactive prevention rather than reactive response.
Different storage durations require differentiated protection strategies to ensure stable performance of sand molds throughout their storage cycle. For short-term storage (e.g., requiring use within a few days), after ensuring basic temperature and humidity control and stacking protection, daily ventilation (during periods of low humidity, such as midday) can be used to maintain fresh air in the warehouse and prevent the gradual accumulation of small amounts of moisture in the enclosed environment. For long-term storage (e.g., for more than a week), in addition to standard protective measures, the entire sand mold should be wrapped with a waterproof, breathable film. The film's breathability prevents residual moisture from escaping and causing mold, while its waterproofness completely isolates the mold from external moisture. Before wrapping, inspect the sand mold for microcracks. If any are present, fill them with a specialized repair agent to prevent moisture from seeping in.
During sand mold storage, ventilation and moisture control must be balanced, avoiding problems caused by excessive ventilation or excessive airtightness. If a warehouse remains completely sealed for extended periods, small amounts of volatile substances left over from the sand mold making process may accumulate inside. While this doesn't directly lead to moisture absorption, it may affect the subsequent casting performance of the sand molds. Excessive ventilation (such as leaving doors and windows open for extended periods) allows large amounts of humid air to enter, disrupting the stable temperature and humidity environment. Therefore, ventilation should adhere to the principle of "small amounts, frequent ventilation, and appropriate timing." Each ventilation session should be kept within a reasonable range, preferably during periods when the outside temperature and humidity are similar to those inside the warehouse, such as mornings or afternoons on sunny days. This allows for air exchange without significantly impacting the temperature and humidity inside the warehouse, maintaining a stable environment.
In the event of sudden temperature and humidity anomalies (such as dehumidification equipment failure or a water leak in the warehouse), immediate emergency measures must be implemented to minimize the impact on the sand molds. If a dehumidification device failure causes a rapid increase in humidity, backup dehumidification equipment should be immediately activated, and sand molds near the faulty area or showing signs of slight moisture absorption should be moved to a dry area. If a localized water leak occurs in the warehouse, the water source must be immediately blocked, the accumulated water must be cleared, and the sand molds near the leaking area must be inspected. If the surface of the sand mold is only slightly damp, it can be dried in a ventilated and dry place and then reassessed for strength. If the interior has absorbed moisture, causing a significant decrease in strength, it is necessary to determine whether the sand mold is still usable to avoid forcing it into use and affecting the quality of the casting. After emergency treatment, the warehouse's protective measures must be thoroughly inspected and any loopholes repaired to prevent similar problems from recurring, ensuring that the sand mold storage environment is always reliable.
